The present invention is a monocular computer vision technique. The technique is used to aid road vehicle driving for safety. A camera (e.g., camera or camcorder) is installed in a vehicle facing to the road in front of the vehicle to capture a sequence of road/scene images for analyzing the driving situation. The situation includes the distance to a front obstacle or vehicle, the speed of the vehicle, and the left/right location of the vehicle in a road lane. If a danger situation is arisen, the sound and/or light alarm will arise to warn the driver for safety.
Safe traffic is important to the property of an individual and the stability of human society. Driving a car out to work or travel is trivial nowadays. Sometimes, persons lose their attention during driving a car; especially, for a long-distance or a high-speed driving, many danger situations are then arisen. If there is a mechanism to alarm the driver and provide some useful information to judge by the driver in these situations, the danger is therefore avoided.
Several techniques have been proposed for the purposes of safe driving. In most previous proposed techniques, an ultrasonic range finder or laser radar was equipped on a car to detect the obstacles in front of the car. The equipments are expensive, have only a special function, and are not easily used. Other techniques had equipped a pair of cameras on a car and then utilized the stereo vision method to guide the navigation; however, this vision system is still complicated, working slowly, and expensive. If we can only equip a camera to detect the obstacles in front of the car and to guide the navigation, the vision system will be simpler, cheaper, and easy to practice for safe driving.
The left/right location of a vehicle in a road lane is also important to the driver during driving on a road; especially for that the driver can""t concentrate his/her attention on the driving. To the detection of the left/right location in a lane, someone had proposed a method by equipping one camera on each side of the car to detect lines on both sides of the current lane; however, such equipments are still complicated and more expensive. It had better detect the left/right location of a vehicle in a road lane only using a camera.
The present invention is used for aiding road vehicle driving to improve the driving safety, to reduce the traffic accident, and to avoid the loss of lives and property. The invention technique only installs a camera in a vehicle facing to the front of the vehicle to capture a sequence of road/scene images, then utilizes the monocular computer vision method to acquire the driving situation. The situation includes the distance to a front obstacle or vehicle, the speed of the vehicle, and the left/right location of the vehicle in a road lane.
In order to attach the mentioned purposes, the present invention proposes a monocular computer vision technique to aid road vehicle driving for safety. The invention technique only installs a camera in a vehicle facing to the front of the vehicle and then processes the following steps:
i. using the camera to capture a sequence of road/scene images;
ii. processing and analyzing the sequence of images using the monocular computer vision method; and
iii. acquiring the driving situation for the vehicle based on the analysis results of the computer vision method.
As the described monocular computer vision technique for aiding road vehicle driving, the camera is a camera, TV camera, digital camera, camcorder, or digital camcorder. The capture device connects a computer and directly transmits the captured images or video into the computer for computer vision analysis.
As the described monocular computer vision technique for aiding road vehicle driving, the vehicle is a car, bus, or truck.
As the described monocular computer vision technique for aiding road vehicle driving, the camera is fixed on the front of a vehicle, the device is facing to the road in front of the vehicle, and the contents of the images are the road and scene in front of the vehicle.
As the described monocular computer vision technique for aiding road vehicle driving, the procedure for the monocular computer vision method contains:
i. detecting the distance to a front obstacle or vehicle by analyzing the image sequence;
ii. estimating the vehicle speed based on a continuous image sub-sequence of the sequence; and
iii. determining the left/right location of the vehicle in the current lane.
As the described monocular computer vision technique for aiding road vehicle driving, the detection of the distance to a front obstacle or vehicle consists of the following steps:
i. from each image to extract the lines on both sides of the current lane and then find the intersection of these two lines; the intersection point is just the vanishing point of the lane;
ii. from the vanishing point and the known focal length of the camera lens to find the pitch and yaw angles of the lane lines with respect to the camera coordinate system;
iii. from the pitch angle and the height of the camera to calculate the distance from the camera location to the point which is the intersection of the camera optical axis and the road plane;
iv. from each image to find horizontal lines to indicate the intersections of the rear wheels of front vehicles and the road, select a nearest horizontal line that overlaps the current lane, and judge that the horizontal line is located above or below the image center;
v. from the known camera focal length, camera height, pitch angle, and the vertical distance from the horizontal line to the image center to find the road distance from the camera location to the rear wheel of the front vehicle or obstacle.
As the described monocular computer vision technique for aiding road vehicle driving, the vehicle speed is computed based on the detection of the distance to a front vehicle. At first, a terminal point of a dashed lane line is found in any continuous image sub-sequence. For the images, the distances from the camera location to the terminal point are calculated respectively. The vehicle speed is just derived from the distance difference dividing by the time difference for the images.
As the described monocular computer vision technique for aiding road vehicle driving, the left/right location of the vehicle in a road lane is computed from the ratio of two distances which are from the midpoint of the image lower border to the intersection points of the extended image lower border and the two lines of the current lane.
As the described monocular computer vision technique for aiding road vehicle driving to acquire the driving situation, the situation includes the distance to a front obstacle or vehicle, the speed of the vehicle, and the left/right location of the vehicle in a road lane.